I&E Wheelchair Design Seminar: Friday, October 17, 1975

I Debby Kaplan, along with a group of law students, is working on a study of dealers and manufacturers of motorized wheelchairs.

A. They will propose regulations on monopolistic practices within business corporations.

B. Bob Lamson, also working on this project, wants to work on a questionnaire to find out more about defective products.
Bob Lamson
2308-A Dwight Way
Berkeley, Ca. 94704

II Wheels and tires

A. Ted Diaz - Solid rear tires are not effective outdoors because they don't have give and spokes on wheel assemblies bend.

B. Wheel size and design

1. Thin tires will decrease mobility.

2. Willie Winocur: He has wide tires for traction (5 inches wide, in comparison to the regular Advanced tires which are 3
inches wide). He does have some problems with skidding. With treads, either diamond or nobby, the grip is better in rainy
weather. However Willie is not sure about the extent of the manoeuvreability of treads on slippery surfaces.

a. Herb W. - He talked with Rich Weiss from Advanced/National about tires. Weiss feels that nobby tread tires have best overall
performance, but may have problems in special use.

b. Willie W. - Nobbies and other treads are not as good indoors because they grip rugs.

c. Doug Bollinger - EJ power chairs are harder to manoeuvre on rugs, as the weight of the EJ is not distributed over a wide
area.

C. Tires on rugs

1. Herb - Using the 12 volt controls on the Advanced may make travelling on rugs easier.

2. Carmen Paz - Tank-like tires may make travel on rugs easier. However Herb does not think that this type of tire would make
travel easier.

D. Tire on curbs

1. The motors and power of a chair are important factors in getting over curbs, while the diameter of the tire has less effect
in mounting curbs.

2. Hale Zucas - Running starts to get over curbs are not successful. It is easier to stop, then go over the curb.

3. Doug B. - The ride on the Advanced is much smoother than on the EJ, and can make bigger curbs than the EJ. Tire pressure
is important in getting up curbs.

― 2 ―

4. Ted Diaz - The bounce in tires helps getting over curbs.

F. Earl McKeever - A caterpillar drive with a low center of gravity could climb stairs. The Germans designed a wheelchair
with this drive, but going down stairs is difficult, and street travel is a problem. Also this wheelchair could not turn easily.

G. For good grip, the contact point must be as square as possible. Long, thin tires will slip.

III Electronic system

A. Vince - The size of the wheelchair will be determined by the electronic system.

1. Herb - Financing research on electronics is a problem, but we will apply for funding for electronics research.

2. The UC Project worked on the mechanical system first, which made development of the electronic system more difficult.

B. Willie W. - It is really important to develop an improved electronic system, with cables laid out well, and wire feeding
and connections made better.

C. Herb - The new Advanced is an improved chair. The electronic system, made by Motorrette, now has both a 12 volt and 24
volt electronics system. The forks are new-"Rolls" with different bearings. The new motors are more powerful and durable.
The wiring is tacked down. The gear box is less efficient, but more durable, and because it is not part of the motor, maintenance
and repair is easier. The new Advanced is less noisy.

1. Doug B- Weiss promised to make more powerful motors because the new gears are less powerful.

2. Willie W. - Several persons in the community have written a letter to National about the new gears. It is the manufacturer's
responsibility to supply a choice in parts.

3. Herb - Weiss has developed a new electronic system which should be available in a few months. National has stayed with
transistors because the silicone rectified transistors could not be synchronized and the chair would swerve when going forward.

4. A meeting will be set up with National to show the new Advanced chair at CIL. All persons can ask Rich Weiss about the
chair. Gordon S. needs to be notified so he can look at the new gearbox in advance.

D. The relay systems on wheelchairs are archaic so a new circuitry should be designed.

IV Suspension

A. Herb - Any prototypes must be road tested first.

B. The weight of the wheelchair may be a consideration in getting over curbs.

1. Willie W. - The balance of a chair is important. Weight distribution can affect whether a curb can be climbed.

2. Earl M. - He puts his charger under the chair for balance and to keep the charger out of the way. He would prefer to have
the charger securely mounted.

a. Vince - The jarring of the chair might ruin the charger electronics, so it must be solidly mounted.

b. Herb - By having a charger mounted so it swings out, it will take up too much space.

― 3 ―

c. Earl M. - A charger that swings out is well-ventilated.

C. Front and rear problems are more important than lateral suspension. Jack Rowan has suggested investigating race car suspension
which prevents outside drop by having a low center of gravity to see if any comparisons can be made for wheelchairs.

D. Because the battery tray is mounted low in back, the gravity is low. By bringing the battery up, greater balance is established.
It will be essential to obtain small batteries (which will take less space).

E. All people are different in trunk size and sit differently.

F. If chairs are low, persons can not get out easily. A chair with a low center of gravity must be able to go up and down.

V Forks

A. "Davis" forks have leverage. But the springs bottom out, which helps the frame to break under the pressure.

1. Doug B. - The chair frame does not have to be constructed at right angles.

2. Fluid dampening devices can be built into the system instead of using springs.

B. When going off curbs, a chair with pneumatics and "Davis" forks have "soft suspension", so will drop down. On the EJ chairs
which are high and narrow, a person can lose balance easily.

VI Safety features

A. Safety features should be an option.

B. Lights

1. Lights should be incorporated in the design of the wheelchair, so they are less noticeable than they now are on the EJ
chairs.

2. Hale Zucas would like to see a test of light systems and reflectors to determine the effectiveness of both. If reflectors
are as effective as the red lights, they would be less costly to install.

3. Willie W. - Using lights does not reduce the range of the chair.

C. Herb - Directional signals can be used on sidewalks.

1. However signals may be confusing when used on a sidewalk.

2. Signals may not be effective on streets as chairs are too low for car drivers' view.

D. Horns

1. Horns are important if a car is backing out of an alley or driveway.

2. Soft and loud horns are a good idea.

E. Seat belts

1. Places to install belts should be optional.

2. What should the tensile strength of belts be?

a. When riding in a van, a secure belt is needed (which can be optional). The automotive seat belts are too hard for most
disabled persons to fasten. Tom Fussy knows about magnetic seat belts made by Kungel which he will investigate.

b. Robin-Aids has a velcro seat belt with a loop that increases the strength.

c. On the EJ chairs, only one screw holds each belt, so it is easy for the belt to tear out.

VII Folding power wheelchairs

A. A chair that folds up can not hold batteries.

B. The back of chairs can fold down, so the heigth of the chair is at arm level.

― 4 ―

VIII Chair dimension

A. Doug B. does not have problems with the clearance of his Advanced.

B. If the footrests are brought back (to cut dimension), they may be too close to casters. With a single foot rest and a bar
in the middle, the rest can be brought back.

C. Narrow chairs can get through doorways. Yet if chairs are too narrow, they will tip easily.

D. Seat size

1. Herb - EJ has 16 inch and 18 inch seats which accomodate most people. Herb has a 16 inch chair seat, but he needs about
one additional inch in width.

E. In homes, either the chair axles or the outside edges of forks damage doorways and walls. Streamline forks may be helpful.

1. Vince G. - By supplying options on tires and footrests, we can offer a chair for either indoor or outdoor use.

2. Meyra, a German manufacturer, has 1,000 different types of wheelchairs.

B. The 1959 Sunbeam can recline in several positions. It could be used for a model for wheelchair seats.

XI Seat angle

A. With steep seats, the legs must be raised up. However this creates pressure sore problems, and puts a lot of pressure on
the tailbone. Also a person's back hurts, so backs should have a convex surface.

XII Controls
Jack R. - With microswitches, he had to keep weight down at all times to operate controls.

B. A new driving concept, using wrists, is needed.

1. Some persons use T-Bars.

2. Debbie Dinardo has controls reversed because it is easier for her to pull backwards on her switch.

C. By mounting the control box over the lap, a person can't get close to tables and the lap area can not be used. Ginny Mackenzie
has a lap control box which swings out.

XIII Additional Comments.

A. Jack R. used a chair developed by a friend in Stanford.

1. The chair had small, 10 inch diameter front wheels.

2. He could make sharp turns.

3. UCLA is making a chair with Servo steering (full power steering).

― 5 ―

B. Willie W. has developed an emergency brake, but different types of actuators need to be tested. An actuator should be developed
utilizing a push button. By creating a suction cup device, a persons can actuate by putting her had back.

C. The CIL Design Project should seek further input from clients. Perhaps we can place an ad in Accent On Living, asking the readership to respond to a questionnaire about wheelchairs.